徒骇河沉水植物腐烂对上覆水体中营养盐形态变化影响

Impact of Decomposition of Submerged Macrophytes on Nutrient Speciation Concentration in Overlying Water of Tuhai River

将杀青后的菹草(Potamogetoncrispus)和金鱼藻(Ceratophyllumdemersum)剪成1 cm左右分别浸泡于装有原上覆水样的烧杯中,并置于27℃和10℃的恒温培养箱中,在不同时刻测定上覆水体的pH、溶解氧(DO)和不同形态氮磷营养盐的浓度。结果表明:由于菹草和金鱼藻的腐烂分解,上覆水体pH呈现先下降后上升的变化趋势,溶解氧急剧降低,氮磷浓度增加。氮浓度的增加以有机氮为主,平均约占63%,氨氮次之,约占25%;磷浓度的增加在实验前期以颗粒态磷为主,平均约占60%,而在实验后期以可溶性总磷为主,约占65%。在27℃下,氮磷形态浓度主要呈现先上升后下降的趋势;在10℃下,氮磷形态浓度主要表现为持续上升。硝氮和亚硝氮浓度的变化与溶解氧浓度变化具有较好的一致性。

Using the method of laboratory simulation,the impact of decomposition of two dominant submerged macrophytes in Tuhai River on nutrient speciation concentrations in overlying water at different temperatures was studied.Results showed that in the decomposition process of Potamogeton crispu and Ceratophyllum demersum,pH of the overlying water declined and then rose,and concentrations of DO descended rapidly.Concentrations of nitrogen and phosphorus in overlying water increased,and as for nitrogen,organic nitrogen was the main form,and followed by ammonia nitrogen.As for phosphorus,in the earlier stage of the experiment,particulate phosphorus was the main form,but in the later stage dissolved phosphorus was the main form.At 27 ℃,the concentrations of organic nitrogen,ammonia nitrogen,particulate phosphorus and dissolved phosphorus in the overlying water increased at the beginning of the composition and then declined.However,at 10 ℃,the concentrations of organic nitrogen,ammonia nitrogen and dissolved phosphorus were continuously increasing.At the end of experiment,the accumulation of both phosphorus and nitrogen in overlying water at 10 ℃ was obviously higher than that at 27 ℃.Nitrate and nitrite nitrogen concentration at 27 ℃ and 10 ℃ both had the similar change trend with the concentrations of DO in the overlying water.